common sw_engine: gather scattered stroking composition.

There are two branches for completing stroke composition between the canvas and sw_engine.

It is necessary to centralize the task on the canvas engine side so that
we can maintain the logic without confusion.

src/lib/sw_engine/tvgSwRenderer.cpp

@@ -125,10 +125,6 @@ struct SwShapeTask : SwTask
             }
         }
 
-        //Decide Stroking Composition
-        if (visibleStroke && visibleFill && opacity < 255) cmpStroking = true;
-        else cmpStroking = false;
-
         //Fill
         if (flags & (RenderUpdateFlag::Gradient | RenderUpdateFlag::Transform | RenderUpdateFlag::Color)) {
             if (visibleFill || clipper) {
@@ -143,7 +139,7 @@ struct SwShapeTask : SwTask
             if (auto fill = rshape->fill) {
                 auto ctable = (flags & RenderUpdateFlag::Gradient) ? true : false;
                 if (ctable) shapeResetFill(&shape);
-                if (!shapeGenFillColors(&shape, fill, transform, surface, cmpStroking ? 255 : opacity, ctable)) goto err;
+                if (!shapeGenFillColors(&shape, fill, transform, surface, opacity, ctable)) goto err;
             } else {
                 shapeDelFill(&shape);
             }
@@ -158,7 +154,7 @@ struct SwShapeTask : SwTask
                 if (auto fill = rshape->strokeFill()) {
                     auto ctable = (flags & RenderUpdateFlag::GradientStroke) ? true : false;
                     if (ctable) shapeResetStrokeFill(&shape);
-                    if (!shapeGenStrokeFillColors(&shape, fill, transform, surface, cmpStroking ? 255 : opacity, ctable)) goto err;
+                    if (!shapeGenStrokeFillColors(&shape, fill, transform, surface, opacity, ctable)) goto err;
                 } else {
                     shapeDelStrokeFill(&shape);
                 }
@@ -490,30 +486,15 @@ bool SwRenderer::renderShape(RenderData data)
 
     if (task->opacity == 0) return true;
 
-    uint32_t opacity;
-    Compositor* cmp = nullptr;
-
-    //Do Stroking Composition
-    if (task->cmpStroking) {
-        opacity = 255;
-        cmp = target(task->bounds(), colorSpace());
-        beginComposite(cmp, CompositeMethod::None, task->opacity);
-    //No Stroking Composition
-    } else {
-        opacity = task->opacity;
-    }
-
     //Main raster stage
     if (task->rshape->stroke && task->rshape->stroke->strokeFirst) {
-        _renderStroke(task, surface, opacity);
+        _renderStroke(task, surface, task->opacity);
-        _renderFill(task, surface, opacity);
+        _renderFill(task, surface, task->opacity);
     } else {
-        _renderFill(task, surface, opacity);
+        _renderFill(task, surface, task->opacity);
-        _renderStroke(task, surface, opacity);
+        _renderStroke(task, surface, task->opacity);
     }
 
-    if (task->cmpStroking) endComposite(cmp);
-
     return true;
 }
 

src/lib/tvgSceneImpl.h

@@ -63,6 +63,7 @@ struct Scene::Impl
     RenderData rd = nullptr;
     Scene* scene = nullptr;
     uint8_t opacity;                     //for composition
+    bool needComp;                       //composite or not
 
     Impl(Scene* s) : scene(s)
     {
@@ -109,10 +110,12 @@ struct Scene::Impl
 
     RenderData update(RenderMethod &renderer, const RenderTransform* transform, uint32_t opacity, Array<RenderData>& clips, RenderUpdateFlag flag, bool clipper)
     {
+        if ((needComp = needComposition(opacity))) {
             /* Overriding opacity value. If this scene is half-translucent,
                It must do intermeidate composition with that opacity value. */
             this->opacity = static_cast<uint8_t>(opacity);
-        if (needComposition(opacity)) opacity = 255;
+            opacity = 255;
+        }
 
         this->renderer = &renderer;
 
@@ -136,7 +139,7 @@ struct Scene::Impl
     {
         Compositor* cmp = nullptr;
 
-        if (needComposition(opacity)) {
+        if (needComp) {
             cmp = renderer.target(bounds(renderer), renderer.colorSpace());
             renderer.beginComposite(cmp, CompositeMethod::None, opacity);
         }

src/lib/tvgShapeImpl.h

@@ -36,7 +36,8 @@ struct Shape::Impl
     RenderData rd = nullptr;            //engine data
     uint32_t flag = RenderUpdateFlag::None;
     Shape* shape;
-    bool needComp;                      //for composition
+    uint8_t opacity;                    //for composition
+    bool needComp;                      //composite or not
 
     Impl(Shape* s) : shape(s)
     {
@@ -56,7 +57,7 @@ struct Shape::Impl
 
         if (needComp) {
             cmp = renderer.target(bounds(renderer), renderer.colorSpace());
-            renderer.beginComposite(cmp, CompositeMethod::None, 255);
+            renderer.beginComposite(cmp, CompositeMethod::None, opacity);
         }
         ret = renderer.renderShape(rd);
         if (cmp) renderer.endComposite(cmp);
@@ -65,12 +66,14 @@ struct Shape::Impl
 
     bool needComposition(uint32_t opacity)
     {
-        //In this case, paint(shape) would try composition by backends. (See: SwShapeTask::run())
+        if (opacity == 0) return false;
-        //TODO: that composition should be moved here?
-        if (opacity < 255) return false;
 
-        //Shape composition is only necessary when stroking is valid.
+        //Shape composition is only necessary when stroking & fill are valid.
         if (!rs.stroke || rs.stroke->width < FLT_EPSILON || rs.stroke->color[3] == 0) return false;
+        if (!rs.fill && rs.color[3] == 0) return false;
+
+        //translucent fill & stroke
+        if (opacity < 255) return true;
 
         //Composition test
         const Paint* target;
@@ -83,7 +86,12 @@ struct Shape::Impl
 
     RenderData update(RenderMethod& renderer, const RenderTransform* transform, uint32_t opacity, Array<RenderData>& clips, RenderUpdateFlag pFlag, bool clipper)
     {     
-        needComp = needComposition(opacity);
+        if ((needComp = needComposition(opacity))) {
+            /* Overriding opacity value. If this scene is half-translucent,
+               It must do intermeidate composition with that opacity value. */ 
+            this->opacity = static_cast<uint8_t>(opacity);
+            opacity = 255;
+        }
 
         rd = renderer.prepare(rs, rd, transform, opacity, clips, static_cast<RenderUpdateFlag>(pFlag | flag), clipper);
         flag = RenderUpdateFlag::None;